The present invention relates to a spherical surface machining apparatus for performing grinding and polishing so as to form a spherical surface of an optical lens, a mirror or the like.
Conventionally, machining of optical lenses, mirrors and so on are processed by first forming the surface of material of lenses, mirrors and so on (hereinafter simply called "the lens material") in a spherical shape by a rough grinding machine or a so-called grinding machine and lapping the spherically formed lens material by a polishing machine. Such a grinding machine, as shown in FIG. 1, holds a lens material 1 on a rotatable grinding holder a and grinds the lens material 1 with a diamond tool d mounted at the tip of a cup-shaped wheel c. This grinding machine 1, as is capable of forming convex, concave and flat surfaces, may be employed in a variety of uses. Even though the accuracy is not so high, it is generally used in a preprocessing which does not require such a high accuracy.
However, the above-mentioned grinding machine requires a complicated procedure of obtaining a synthetic spherical form, and performs a line cut, due to a strip type blade portion of the diamond tool d of the cup-shaped wheel c, which cannot provide so good finished surfaces as a surface cut, thereby giving rise to a grave problem in a lens lapping processing in which the accuracy in the preprocessing exerts great influences on the stability of the postprocessing.
To solve the above-mentioned problems, the present assignee has provided a spherical surface machining apparatus for optical lenses, mirrors and so on, as shown in FIG. 2. This apparatus allows selection of a reference cam 29 from those respectively having a different spherical surface of cam profile in accordance with desired spherical surface machining. In addition, a spindle 12 of a grinding plate 10 can be moved in an axial direction and fixed so as to meet the requirement of the spherical surface machining, which permits freely changing the spherical center swinging trajectory of the spindle 10 of the grinding plate 10, whereby any lens material 1 can be arbitrarily processed to form a desired spherical surface.
The above-mentioned apparatus can be used for any use, more specifically, for forming convex, concave and flat surface, and does not require complicated handling for setting the spherical surface. Further, since this apparatus performs a surface cut, a machining time can be largely reduced and highly accurate finished surface can be provided compared with conventional apparatus. Further, this apparatus can be used for polishing the lens material, in addition to grinding by changing a lens chucking method to provide a freedom for a lens attachment.
The above-mentioned spherical surface machining apparatus, though providing easy surface grinding while maintaining versatility and high accuracy, is constructed such that two reference cams 29 having highly accurate curve surface of the cam profile are disposed on lateral sides of the grinding plate 10, wherein the two reference cams 29 must be positioned symmetrically with respect to the grinding plate 10. However, such positioning is a quite time-consuming operation. Moreover, a swinging movement of the spindle 12 of the grinding plate 10 is performed by a swing apparatus b provided separately from a swing body 20. Therefore, this apparatus, in a complicated construction, not only requires a long time for exchanging or adjusting the reference cams 29 but also is quite expensive and large.